Design and implementation of differential cascode voltage switch with pass-gate (DCVSPG) logic for high-performance digital systems

Abstract

In this paper, a new high-speed circuit technique called differential cascode voltage switch with pass-gate (DCVSPG) logic tree is presented. The circuit technique is designed using a pass-gate logic tree in DCVSPG instead of the nMOS logic tree in the conventional DCVS circuit, which eliminates the floating node problem. By eliminating the floating node problem, the DCVSPG becomes a new type of ratioless circuit, and it also provides superior performance with less power dissipation and better silicon area tradeoff. The basic DCVSPG design technique, the methodology for optimization, and synthesis of the pass-gate logic tree are described. The standard cell library development taking advantage of the dual-rail outputs of DCVSPG gates is also discussed. The performance comparisons with other existing pass-gate circuit techniques [complimentary pass-transistor logic (CPL), double pass-transistor logic (DPL), and swing restored pass-transistor logic (SRPL)] are presented. For more robust design, the DCVSPG with inverter buffers is also the best choice. A Viterbi macro design using the DCVSPG circuit technique is demonstrated. The process that the design is based upon is a 0.5-/spl mu/m CMOS technology with 0.25-/spl mu/m effective channel length and five layers of metal. This macro can run up to 500 MHz at the nominal process condition. In comparison with other existing dynamic circuit techniques, the results also clearly show that the dynamic DCVSPG has the superior power-delay performance.